1. Field of the Invention
This invention relates to check valves and, more particularly, to a check valve having a manually releasable valve and particularly adapted for use in the aircraft spray business.
2. Description of the Prior Art
U.S. Pat. No. 4,682,625, the inventor of which is the inventor of the present apparatus, discloses a spring loaded shutoff valve apparatus designed primarily for crop dusting purposes. The valve apparatus of the '625 patent includes a piston movable in a stepped bore. The stepped bore includes a lesser bore portion having an inside diameter which is substantially the same as the outer diameter of the piston. Movement of the piston into a greater bore portion having a substantially larger diameter than the diameter of the piston allows fluid to flow into the stepped bore and through a connecting bore outwardly of the valve housing. The piston is spring biased into the lesser diameter bore portion of the stepped bore to prevent fluid flow.
As is well known and understood in crop dusting, the fluid to be sprayed typically contains debris and the like. The debris may clog a valve or at least result in dripping until the valve is unclogged.
In the prior art, it is generally necessary to disassemble the valve to clear debris. The disassembly results in the contamination of the hands of the person who disassembles the valve.
The present invention allows debris to be cleared without the disassembly of the valve and without the contamination of a worker.